One of the characteristics of God’s perfection is his reputation. God is not the same as man in that he was not created. He is self-existent, he is entirely self-sufficient and not dependent or contingent upon anything else. Basically, what that means is that he does not change. He is the same yesterday, today, and for the rest of eternity. Therefore, his character or attributes are constant and can be relied upon to be the same in every situation.
I believe the reason God took the time to develop a relationship with Abraham was so that he could establish his reputation in dealing with sinful man. Psalm 106 is a confession of Israel’s long history of rebellion and a prayer for God to once again save his people. It says in Psalm 106:8, “Nevertheless, he saved them for his name’s sake, that he might make his mighty power to be known.”
God’s ability to do miraculous things is what sets him apart from every other being. That in and of itself is enough to qualify him to be God, but it is not that he can do a miracle, God can do anything. His power is unlimited. Most people, even those that know God and have a personal relationship with him, are not aware of what God is capable of. God wanted Abraham and the rest of the world to know that he could do the impossible and when he made a promise, it was certain to be kept.
God promised Abraham that his descendants would dwell in the land known as Canaan. He even told Abraham ahead of time that his children would end up in slavery and God would deliver them. He even told Abraham the length of time they would be held in bondage (Genesis 15:13). In spite of the Israelites rebellion and lack of faith, God kept his promise and he will keep his promise to you too.